Securing

Thunderbird sends your system's internal IP address to the configured SMTP server as an argument to the HELO/ELHO SMTP command. This value can be overridden by setting mail.smtpserver.default.hello_argument to, for example, localhost. Setting this value may increase the spam score of messages you send. See [1] and [2].

This can be overridden with network.protocol-handler.warn-external in the #Config Editor

If the following is all set to false (default), set them to true and Thunderbird will ask you which application to use when you click on a link (remember to also check "Remember my choice for .. links").

Plain Text mode and font uniformity

Plain Text mode lets you view all your emails without HTML rendering and is available in View > Message Body As. This defaults to the Monospace font but the size is still inherited from original system fontconfig settings. The following example will overwrite this with Ubuntu Mono of 10 pixels (available in: ttf-ubuntu-font-family).

Remember to run fc-cache -fv to update system font cache. See Font configuration for more information.

Export and Import

Before you start with Importing or Exporting tasks, backup your complete ~/.thunderbird profile:

$ cp -R ~/.thunderbird /to/backup/folder/

If your accounts are broken or you want to join two different Thunderbird installations, you better install one Import and Export AddOn (eg. ImportExportTools AddOn) to both Thunderbird installations and following this just export and import all your data to the new installation.

Change the default sorting order

Thunderbird (up to at least 31.4.0-1) sorts mail by date with the oldest on top without any threading. While this can be changed per folder, it is easier to set a sane default instead as described here.

Some limitations up to at least 31.4.0-1: only the "tmp" and "cur" directories are supported. The "new" directory is completely ignored. The read state of mails are stored in a separate ".msf" file, so initially all local mail using Maildir will be marked as unread even when located in the "cur" directory.

Troubleshooting

LDAP Segfault

Error: Incoming server already exists

It seems Thunderbird (v24) still has that bug which pops up with "Incoming server already exists" if you want to reinstall a previously deleted account with the same account data afterwards. Unfortunately, if you get this error you can now only clean reinstall Thunderbird:

1. Make a backup of your current profile:

$ cp -R ~/.thunderbird /to/backup/folder/

2. Export all your Accounts, Calendar and Feeds via an AddOn like it's written in Export section of this Wiki.

Thunderbird UI freezes when receiving a new message

If Thunderbird is configured to show an alert when a new message arrives, or at launch, the lack of a notification daemon may freeze the interface (white screen) for many seconds. You can solve this issue by disabling alerts or installing a notification server.

LC_TIME environment variable not respected

Thunderbird should use the LC_TIME environment variable for localization, but it might not do so in all contexts. Some problems can be mitigated by setting Edit > Preferences > Advanced > Date and Time Formatting to Regional settings locale, a setting which was introduced in Thunderbird 56. However, there is a bug report for this issue.